Poloidal ULF oscillations in the dayside magnetosphere: a Cluster study

Eriksson, P. T. I.; Blomberg, Lars G.; Walker, A. D. M.; Glaßmeier, Karl‐Heinz

doi:10.5194/angeo-23-2679-2005

Cited by 28 publications

(28 citation statements)

References 24 publications

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“…Such large azimuthal wave numbers are expected for poloidal oscillations (e.g. Radoski, 1967) and observed by Eriksson et al (2005b) recently.…”

Section: Phenomenology Of the Wave Activitymentioning

confidence: 99%

“…Here the four CLUSTER spacecraft (Escoubet et al, 1997) represent a very suitable tool to analyze magnetospheric ULF pulsations as shown in a recent study of poloidal ULF pulsations by Eriksson et al (2005b). These spacecraft move through the magnetosphere on polar orbits forming various scaled configurations with distances between 0.016 R E and 2.0 R E .…”

Section: S Schäfer Et Al: Characteristics Of Poloidal Waves: a Clusmentioning

confidence: 99%

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Spatial and temporal characteristics of poloidal waves in the terrestrial plasmasphere: a CLUSTER case study

et al. 2007

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Abstract. Oscillating magnetic field lines are frequently observed by spacecraft in the terrestrial and other planetary magnetospheres. The CLUSTER mission is a very suitable tool to further study these Alfvén waves as the four CLUS-TER spacecraft provide for an opportunity to separate spatial and temporal structures in the terrestrial magnetosphere. Using a large scaled configuration formed by the four spacecraft we are able to detect a poloidal Ultra-Low-Frequency (ULF) pulsation of the magnetic and electric field in order to analyze its temporal and spatial structures. For this purpose the measurements are transformed into a specific field line related coordinate system to investigate their specific amplitude pattern depending on the path of the CLUSTER spacecraft across oscillating field lines. These measurements are then compared with modeled spacecraft observations across a localized poloidal wave resonator in the dayside plasmasphere. A detailed investigation of theoretically expected poloidal eigenfrequencies allows us to specify the observed 16 mHz pulsation as a third harmonic oscillation. Based on this we perform a case study providing a clear identification of wave properties such as an spatial scale structure of about 0.67 R E , the azimuthal wave number m≈30, temporal evolution, and energy transport in the detected ULF pulsations.

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“…Such large azimuthal wave numbers are expected for poloidal oscillations (e.g. Radoski, 1967) and observed by Eriksson et al (2005b) recently.…”

Section: Phenomenology Of the Wave Activitymentioning

confidence: 99%

Section: S Schäfer Et Al: Characteristics Of Poloidal Waves: a Clusmentioning

confidence: 99%

Spatial and temporal characteristics of poloidal waves in the terrestrial plasmasphere: a CLUSTER case study

et al. 2007

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“…Poloidal ULF waves are often observed with satellites (Eriksson et al, 2005;Schäfer et al, 2007) and radars (Yeoman et al, 2000). There are some hints that the waves are generated by substorm injected particles drifting in the magnetosphere.…”

Section: Introductionmentioning

confidence: 99%

Pc5 waves generated by substorm injection: a case study

2008

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Abstract. We analyzed the spectral-polarized characteristics of Pc5 ULF waves observed on 17 September 2000 after the 03:20:25 UT substorm onset with the satellites GOES 8 and 10 located east and west of the onset location. In the course of the event, the wave polarization changed from mixed (between toroidal and poloidal) to poloidal, and then to mixed again. The hodogram of magnetic field oscillations rotated counterclockwise at GOES 8, and clockwise at GOES 10. It is suggested that the satellites detected the waves generated by the substorm injected clouds of the charged particles drifting in the magnetosphere in the opposite azimuthal directions: GOES 8 (located east of the substorm onset) detected the wave generated by an electron cloud, and GOES 10 (west of the onset) detected the wave generated by a positive ion cloud. This interpretation is confirmed by the energetic particles data recorded by LANL satellites.

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“…Dai et al (2015) noted that the effect of the plasmapause on the radial transmission of the poloidal waves is caused by the fact that the Alfvén speed changes rapidly across the radial direction. Eriksson et al (2005) reported three cases of poloidal Pc5 pulsations with large azimuthal number (m = 100) waves observed by Cluster that occurred in the dayside magnetosphere during magnetically quiet times from L = 4 to L = 6. They studied observations from LANL satellites for signs of proton injection prior to, or during the observed ULF events but none of the events showed any sign of enhanced proton flux.…”

Section: Introductionmentioning

confidence: 99%

Multipoint spacecraft observations of long-lasting poloidal Pc4 pulsations in the dayside magnetosphere on 1–2 May 2014

et al. 2016

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Abstract. We use magnetic field and plasma observations from the Van Allen Probes, Time History of Events and Macroscale Interactions during Substorms (THEMIS) and Geostationary Operational Environmental Satellite system (GOES) spacecraft to study the spatial and temporal characteristics of long-lasting poloidal Pc4 pulsations in the dayside magnetosphere. The pulsations were observed after the main phase of a moderate storm during low geomagnetic activity. The pulsations occurred during various interplanetary conditions and the solar wind parameters do not seem to control the occurrence of the pulsations. The most striking feature of the Pc4 magnetic field pulsations was their occurrence at similar locations during three of four successive orbits. We used this information to study the latitudinal nodal structure of the pulsations and demonstrated that the latitudinal extent of the magnetic field pulsations did not exceed 2 Earth radii (R E ). A phase shift between the azimuthal and radial components of the electric and magnetic fields was observed from Z SM = 0.30 R E to Z SM = −0.16 R E . We used magnetic and electric field data from Van Allen Probes to determine the structure of ULF waves. We showed that the Pc4 magnetic field pulsations were radially polarized and are the secondmode harmonic waves. We suggest that the spacecraft were near a magnetic field null during the second orbit when they failed to observe the magnetic field pulsations at the local times where pulsations were observed on previous and successive orbits. We investigated the spectral structure of the Pc4 pulsations. Each spacecraft observed a decrease of the dominant period as it moved to a smaller L shell (stronger magnetic field strength). We demonstrated that higher frequencies occurred at times and locations where Alfvén velocities were greater, i.e., on Orbit 1. There is some evidence that the periods of the pulsations increased during the plasmasphere refilling following the storm.

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Poloidal ULF oscillations in the dayside magnetosphere: a Cluster study

Cited by 28 publications

References 24 publications

Spatial and temporal characteristics of poloidal waves in the terrestrial plasmasphere: a CLUSTER case study

Spatial and temporal characteristics of poloidal waves in the terrestrial plasmasphere: a CLUSTER case study

Pc5 waves generated by substorm injection: a case study

Multipoint spacecraft observations of long-lasting poloidal Pc4 pulsations in the dayside magnetosphere on 1–2 May 2014

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